South Africa's Trevor Immelman and Rory Sabbatini played a solid round to make their big lead stand up.
Immelman and Sabbatini combined to shoot a 1-over 73 on Sunday and finished at 13-under 275 to give South Africa its second World Cup title in three years and fifth overall. Ernie Els and Retief Goosen teamed up to win in 2001, when the World Cup was played in Japan.
The South Africans, who each earned US$700,000 for the win, started the alternate-stroke round with a seven-stroke lead over the US team of Jim Furyk and Justin Leonard and France's Thomas Levet and Raphael Jacquelin.
"I normally don't watch the leaderboard much but, with seven shots, it just kind of felt funny. I felt I needed to keep an eye on what was going on," said the 23-year-old Immelman, whose previous best payout was US$460,000 for a second-place finish at this year's Volvo PGA Championship.
Sabbatini had said he would "take 18 pars right now and run" following Saturday's round. The South Africans didn't do that, but finished with two birdies and three bogeys, and that was enough.
"I was pretty certain with four holes to go that we had put ourselves in a really good position," Sabbatini said. "If we stuck with what we were doing and didn't make any blatantly stupid errors out there, we were fine."
England's Paul Casey and Justin Rose who made a final-round challenge for the lead. Ten strokes back at the start of the day, the Englishmen shot a 5-under 67 and settled for second at 9-under 279.
"South Africa -- they were 10 ahead of us at the beginning of the day so we couldn't really realistically look at them," Rose said. "We could look at second and if South Africa had a nightmare, we could be there."
Furyk and Leonard were in contention until going bogey-triple bogey at Nos. 12 and 13. The Americans shot a 3-over 75 and finished in a tie for fifth at 4-under 284.
The trouble started when Furyk hit his tee shot into the water on the 440-yard, par-4 13th.
"We played 17 real solid holes without putts going in, and I got loose on one tee shot and we ended up making a triple bogey on that hole," Furyk said. "Other than that, we played well."
Furyk and Leonard tied for fifth Ireland's Padraig Harrington and Paul McGinley.
Levet and Jacquelin finished 8 under, and Germany's Alex Cejka and Marcel Siem, who held the lead after Thursday's best-ball round, finished fourth at 6 under.
The French team managed just two birdies in the final round.
"It's disappointing," Jacquelin said. "This is the second time France has been beaten by England today. We lost the rugby World Cup semifinal to England and now they've taken second place from us in this tournament."
Sunday's round at the World Golf Championships event, which featured two-man teams from 23 nations, was played in mild, sunny conditions with only a light breeze blowing in off the Atlantic at the 7,296-yard Ocean Course, site of the 1991 Ryder Cup.